source: trunk/doc/html/hello-example.html@ 203

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1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
2<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/examples/hello/hello.doc:5 -->
3<html>
4<head>
5<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
6<title>Hello, World</title>
7<style type="text/css"><!--
8fn { margin-left: 1cm; text-indent: -1cm; }
9a:link { color: #004faf; text-decoration: none }
10a:visited { color: #672967; text-decoration: none }
11body { background: #ffffff; color: black; }
12--></style>
13</head>
14<body>
15
16<table border="0" cellpadding="0" cellspacing="0" width="100%">
17<tr bgcolor="#E5E5E5">
18<td valign=center>
19 <a href="index.html">
20<font color="#004faf">Home</font></a>
21 | <a href="classes.html">
22<font color="#004faf">All&nbsp;Classes</font></a>
23 | <a href="mainclasses.html">
24<font color="#004faf">Main&nbsp;Classes</font></a>
25 | <a href="annotated.html">
26<font color="#004faf">Annotated</font></a>
27 | <a href="groups.html">
28<font color="#004faf">Grouped&nbsp;Classes</font></a>
29 | <a href="functions.html">
30<font color="#004faf">Functions</font></a>
31</td>
32<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Hello, World</h1>
33
34
35<p>
36This example brings up the words "Hello, World" moving up and down,
37and in different colors.
38<p> <hr>
39<p> Header file:
40<p> <pre>/****************************************************************************
41** $Id: hello-example.html 2051 2007-02-21 10:04:20Z chehrlic $
42**
43** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
44**
45** This file is part of an example program for Qt. This example
46** program may be used, distributed and modified without limitation.
47**
48*****************************************************************************/
49
50#ifndef HELLO_H
51#define HELLO_H
52
53#include &lt;<a href="qwidget-h.html">qwidget.h</a>&gt;
54
55
56class Hello : public <a href="qwidget.html">QWidget</a>
57{
58 <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
59public:
60 Hello( const char *text, QWidget *parent=0, const char *name=0 );
61signals:
62 void clicked();
63protected:
64 void mouseReleaseEvent( <a href="qmouseevent.html">QMouseEvent</a> * );
65 void paintEvent( <a href="qpaintevent.html">QPaintEvent</a> * );
66private slots:
67 void animate();
68private:
69 <a href="qstring.html">QString</a> t;
70 int b;
71};
72
73#endif
74</pre>
75
76<p> <hr>
77<p> Implementation:
78<p> <pre>/****************************************************************************
79** $Id: hello-example.html 2051 2007-02-21 10:04:20Z chehrlic $
80**
81** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
82**
83** This file is part of an example program for Qt. This example
84** program may be used, distributed and modified without limitation.
85**
86*****************************************************************************/
87
88#include "hello.h"
89#include &lt;<a href="qpushbutton-h.html">qpushbutton.h</a>&gt;
90#include &lt;<a href="qtimer-h.html">qtimer.h</a>&gt;
91#include &lt;<a href="qpainter-h.html">qpainter.h</a>&gt;
92#include &lt;<a href="qpixmap-h.html">qpixmap.h</a>&gt;
93
94
95/*
96 Constructs a Hello widget. Starts a 40 ms animation timer.
97*/
98
99<a name="f473"></a>Hello::Hello( const char *text, QWidget *parent, const char *name )
100 : <a href="qwidget.html">QWidget</a>(parent,name), t(text), b(0)
101{
102 <a href="qtimer.html">QTimer</a> *timer = new <a href="qtimer.html">QTimer</a>(this);
103<a name="x1640"></a> <a href="qobject.html#connect">connect</a>( timer, SIGNAL(<a href="qtimer.html#timeout">timeout</a>()), SLOT(animate()) );
104<a name="x1639"></a> timer-&gt;<a href="qtimer.html#start">start</a>( 40 );
105
106 <a href="qwidget.html#resize">resize</a>( 260, 130 );
107}
108
109
110/*
111 This private slot is called each time the timer fires.
112*/
113
114void <a name="f474"></a>Hello::animate()
115{
116 b = (b + 1) &amp; 15;
117 <a href="qwidget.html#repaint">repaint</a>( FALSE );
118}
119
120
121/*
122 Handles mouse button release events for the Hello widget.
123
124 We emit the clicked() signal when the mouse is released inside
125 the widget.
126*/
127
128<a name="x1641"></a>void Hello::<a href="qwidget.html#mouseReleaseEvent">mouseReleaseEvent</a>( <a href="qmouseevent.html">QMouseEvent</a> *e )
129{
130 if ( <a href="qwidget.html#rect">rect</a>().contains( e-&gt;<a href="qmouseevent.html#pos">pos</a>() ) )
131 emit clicked();
132}
133
134
135/*
136 Handles paint events for the Hello widget.
137
138 Flicker-free update. The text is first drawn in the pixmap and the
139 pixmap is then blt'ed to the screen.
140*/
141
142void Hello::<a href="qwidget.html#paintEvent">paintEvent</a>( <a href="qpaintevent.html">QPaintEvent</a> * )
143{
144 static int sin_tbl[16] = {
145 0, 38, 71, 92, 100, 92, 71, 38, 0, -38, -71, -92, -100, -92, -71, -38};
146
147 if ( t.isEmpty() )
148 return;
149
150 // 1: Compute some sizes, positions etc.
151 <a href="qfontmetrics.html">QFontMetrics</a> fm = <a href="qwidget.html#fontMetrics">fontMetrics</a>();
152<a name="x1631"></a> int w = fm.<a href="qfontmetrics.html#width">width</a>(t) + 20;
153<a name="x1630"></a> int h = fm.<a href="qfontmetrics.html#height">height</a>() * 2;
154 int pmx = <a href="qwidget.html#width">width</a>()/2 - w/2;
155 int pmy = <a href="qwidget.html#height">height</a>()/2 - h/2;
156
157 // 2: Create the pixmap and fill it with the widget's background
158 <a href="qpixmap.html">QPixmap</a> pm( w, h );
159<a name="x1638"></a> pm.<a href="qpixmap.html#fill">fill</a>( this, pmx, pmy );
160
161 // 3: Paint the pixmap. Cool wave effect
162 <a href="qpainter.html">QPainter</a> p;
163 int x = 10;
164<a name="x1629"></a> int y = h/2 + fm.<a href="qfontmetrics.html#descent">descent</a>();
165 int i = 0;
166<a name="x1633"></a> p.<a href="qpainter.html#begin">begin</a>( &amp;pm );
167<a name="x1636"></a> p.<a href="qpainter.html#setFont">setFont</a>( <a href="qwidget.html#font">font</a>() );
168 while ( !t[i].isNull() ) {
169 int i16 = (b+i) &amp; 15;
170 p.<a href="qpainter.html#setPen">setPen</a>( QColor((15-i16)*16,255,255,QColor::Hsv) );
171 p.<a href="qpainter.html#drawText">drawText</a>( x, y-sin_tbl[i16]*h/800, t.mid(i,1), 1 );
172 x += fm.<a href="qfontmetrics.html#width">width</a>( t[i] );
173 i++;
174 }
175<a name="x1635"></a> p.<a href="qpainter.html#end">end</a>();
176
177 // 4: Copy the pixmap to the Hello widget
178 <a href="qimage.html#bitBlt">bitBlt</a>( this, pmx, pmy, &amp;pm );
179}
180</pre>
181
182<p> <hr>
183<p> Main:
184<p> <pre>/****************************************************************************
185** $Id: hello-example.html 2051 2007-02-21 10:04:20Z chehrlic $
186**
187** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
188**
189** This file is part of an example program for Qt. This example
190** program may be used, distributed and modified without limitation.
191**
192*****************************************************************************/
193
194#include "hello.h"
195#include &lt;<a href="qapplication-h.html">qapplication.h</a>&gt;
196
197
198/*
199 The program starts here. It parses the command line and builds a message
200 string to be displayed by the Hello widget.
201*/
202
203int main( int argc, char **argv )
204{
205 <a href="qapplication.html">QApplication</a> a(argc,argv);
206 <a href="qstring.html">QString</a> s;
207 for ( int i=1; i&lt;argc; i++ ) {
208 s += argv[i];
209 if ( i&lt;argc-1 )
210 s += " ";
211 }
212 if ( s.<a href="qstring.html#isEmpty">isEmpty</a>() )
213 s = "Hello, World";
214 Hello h( s );
215#ifndef QT_NO_WIDGET_TOPEXTRA // for Qt/Embedded minimal build
216 h.<a href="qwidget.html#setCaption">setCaption</a>( "Qt says hello" );
217#endif
218 QObject::<a href="qobject.html#connect">connect</a>( &amp;h, SIGNAL(clicked()), &amp;a, SLOT(<a href="qapplication.html#quit">quit</a>()) );
219<a name="x1650"></a> h.<a href="qwidget.html#setFont">setFont</a>( QFont("times",32,QFont::Bold) ); // default font
220<a name="x1648"></a> h.<a href="qwidget.html#setBackgroundColor">setBackgroundColor</a>( Qt::white ); // default bg color
221 a.<a href="qapplication.html#setMainWidget">setMainWidget</a>( &amp;h );
222 h.<a href="qwidget.html#show">show</a>();
223 return a.<a href="qapplication.html#exec">exec</a>();
224}
225</pre>
226
227<p>See also <a href="examples.html">Examples</a>.
228
229<!-- eof -->
230<p><address><hr><div align=center>
231<table width=100% cellspacing=0 border=0><tr>
232<td>Copyright &copy; 2007
233<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
234<td align=right><div align=right>Qt 3.3.8</div>
235</table></div></address></body>
236</html>
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